Feature Request: Radar (Varia) Auto mode (lights on only when a car is approaching)
I’d like to buy a Karoo, but as far as I understand, there’s currently no automatic mode for radar-controlled lighting.
By that I mean: the light should turn on only when a car is approaching, and then turn off again a few seconds after it has passed.
Garmin has offered this for years via a ConnectIQ app, and Wahoo has it built in since the Roam V2.
It also seems that no third-party extension can provide this, due to API limitations.
Please consider adding this feature. Without it, using a radar light on longer rides becomes difficult because of battery constraints.
Radar lights have become quite popular, and I’m sure every radar user would appreciate this feature— even if they don’t realize it yet. 😊
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If you watch GPLamas Videos, I'd rather buy a second Varia to double the battery life instead of these unreliable ones (I don't know if Bryton was one of them, there are a lot radars now).
@Gregory: Does the Bryton really have an Auto mode on the Karoo? So it only turns on when a car is approaching? Or do you mean the Auto mode, that the light turns on when you start a ride and turns off when it finished?
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@Marco, I use Bryton Gardia R300L ~1 year and I can confirm it has car detection with light on/off when the light is off, auto light start/stop, brake detection, USB-C and good battery. https://global.brytonsport.com/products/gardia-r300l
So, if you have Varia, I understand you want to have this function in Karoo. But if you don't have a radar yet, Gardia is a good alternative for Varia because it has this function now. In my opinion the Gardia's case and mounting accessories are very good quality, maybe better than Varia. Gardia can works with aplication only on a smartphone or standalone (but it has no built-in buzzer). Maybe I'll make a video to show it, but I think it's available online.
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Who says sells Varia?
My today video. Gardia light is in OFF mode. It turns on automatically when car approaches. Mode control is native in Karoo without any additional extensions.
https://1drv.ms/v/c/659b11a95c3b3790/IQBLx_NNdDCAQIGkY6XwB55sAYDs_YIIlxRBvIWG4b_qb7g?e=guRfSb
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I can confirm that the Bryton Gardia has this feature.
Even gplama confirmed that purchasing the Gardia was worthwhile after the initial software updates.
I use it from time to time (especially on my way to work) and don't see much difference from the Varia 515. However, the Gardia loses the Ant+ connection more easily, but this is a common problem with radar devices.
Wahoo has implemented this feature, and it has mostly worked for me, but to be honest, I don't see much point in it for me. That's why I prefer the Karoo, where I can easily turn the backlight on and off, which is more complicated with the Elements (Series 2) or the Gamins (even with a touchscreen).
On the road, I prefer to turn the lights on for safety reasons, but I can turn them off on long cycle paths or gravel roads without traffic. The lights are visible much further than the radar's detection range. For safety reasons, I would always recommend keeping the lights on permanently when there might traffic behind you. That should be more important than battery life.
I believe one of the newer recommended radar devices (Wahoo or Lezyne) also has the desired feature.
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@Thomas you are right, having the light on all the time is safer than only when the radar detects something. The problem is, if you have it on all the time, you'll have no light at all sooner or later. Which could be a major problem. Either on a long ride or if you forget to charge the device after every ride. I often had this problem with my Varia back in the days, but since the Roam V2 introduced this feature, it barely happened.
Anyway, it's good to know that some manufacturers implement the auto feature on the device itself, but it would still be nice to manage it on the Karoo as long as most devices out there don't have it.
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Regarding the auto feature on the device, that's nice, but I would prefer to have it on the computer, because I can easier control the feature: i.e., enable auto-on/off during day time, disable during night time or when it's dark due to overcast or so (-> light always on). I agree that it is safer to have the light on when it is darkish, but the light won't help too much on sunny days. When it is light, I would prefer to have the light off (save battery) but have it on when a car approaches.
My use case is, in addition, somewhat different, because I am located in Germany, where we have very strict bike light regulations. And that's not only for using them but for their features. For example, you cannot buy the Wahoo radar legally in Germany, and the new Sigma Reco has a German-market-specific version (no flashing lights, no auto-on/off!). Thus, it would be great, if the bike computer could assistant here. :-)
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Garmin Varia RTL516 — Radar-triggered Solid Light control by Karoo 3
I would like to request a specific improvement to the Karoo 3 integration with the Garmin Varia RTL516:
Radar-triggered Solid Light control
When the RTL516 is in Standby, the Karoo 3 should automatically switch the RTL516 to Solid when the radar detects an approaching vehicle, and return it to Standby once the vehicle has passed.
Why this is particularly relevant to the RTL516
The RTL516 is the StVZO-oriented Varia model. For this model, the desired behavior is therefore a simple change between Standby and Solid, rather than a flashing mode.
This would allow the radar itself to trigger a visible rear-light response when a vehicle approaches, without requiring the light to remain continuously illuminated throughout the entire ride.
More importantly, the change from Standby to Solid at the moment a vehicle is detected could provide an additional visual cue to the approaching driver and help draw their attention to the cyclist.
The Karoo already provides the required building blocks
Hammerhead already supports Garmin Varia rearview radar via ANT+ and provides control of integrated radar/light devices. The current Karoo OS documentation specifically mentions Auto Control and supported light modes.
Reference: Hammerhead – Karoo OS Rearview Radar Integration
There is already a history of requests for this
This is not an isolated use case. There are several existing Hammerhead community requests concerning radar-controlled Varia lighting:
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Radar (Varia) Auto Mode — lights on only when a car is approaching
Request for the Varia light to turn on when an approaching vehicle is detected and turn off again afterwards. -
Garmin Varia Radar Battery Saving
Request for automatic light activation during radar detection to avoid unnecessary continuous light usage. -
ANT+ Lights / Varia light control
Earlier discussion regarding ANT+ control of Garmin Varia lights and their light modes.
Taken together, these requests show that radar-triggered Varia light control has been a recurring topic in the Karoo community rather than being a completely new use case.
There is also a working community implementation
This functionality has already been demonstrated on Karoo 3 by the open-source project KarooFireFly.
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Garmin Varia RTL515/RTL516 are listed as tested.
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The project implements radar-triggered light control.
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However, this is a third-party/community solution. Software or Karoo OS updates could potentially overwrite, break or disable such an implementation.
A native Karoo OS implementation would therefore be preferable because it could be maintained and supported as part of the official Karoo software.
Reference: KarooFireFly on GitHub
While the community implementation uses a flashing mode where supported, the same principle could be applied to the RTL516 using its Solid mode.
Potential user base
Garmin does not publish model-specific worldwide sales figures for the RTL516, so I would not claim an exact installed base.
However, the RTL516 has been on the market for several years and represents an established StVZO-market Varia model.
Even if only a small percentage of RTL516 owners were to choose a Karoo, this could represent several thousand potential Karoo users worldwide for whom this limitation is currently relevant and who would benefit from this functionality.
More importantly, this is an existing recurring request from Varia/Karoo users rather than a completely new use case.
Suggested blueprint
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Radar clear → RTL516 = OFF / Standby
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Radar detects approaching vehicle(s) → RTL516 = Solid
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Radar clear / vehicle(s) have passed → RTL516 automatically returns to Standby
In short:
Standby → Radar detects vehicle → Solid → Radar clear → Standby
Ideally, this could be exposed as an optional setting:
Radar-triggered Light: ON / OFF
This would provide an additional safety and visibility benefit while also reducing unnecessary battery consumption on longer rides.
I would really appreciate it if Hammerhead could consider adding this functionality natively to Karoo OS.
Thank you very much for your attention and consideration.
Best regards,
Harold.
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